JPS6237409B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to an analog output device that samples and holds a plurality of analog signals and outputs the sample-and-hold signals.

(2) Prior Art An analog output device is known in which a plurality of time-series analog signals are switched and selected by a switching circuit, sampled and held by a sample-and-hold circuit, and outputted. In such a device, it is necessary to constantly check whether the correct signals are being output for all of the plurality of analog signals to improve reliability.

(3) Purpose of the Invention In view of the above points, the purpose of the present invention is to provide an analog output device that constantly checks and monitors analog output signals and performs failure diagnosis.

(4) Embodiment of the Invention FIG. 1 is a configuration explanatory diagram showing an embodiment of the invention.

In the figure, 1 is an input terminal to which a plurality of time-series analog signals are supplied; 2 is a comparator to which the signal supplied to input terminal 1 is supplied to one input terminal;
3 has a plurality of switches 31, ......, 3n,
The first switching circuit 41, .
..., capacitor C1 in the feedback circuit of An, ......,
A plurality of hold circuits including integrators etc. connected to Cn, 51, ......, 5n are hold circuits 41,
......, 4n output terminal 6 has a plurality of switches 61, ......, 6n, which are synchronized with the first switching circuit 3 and hold circuits 41, .
..., 4n and supplies it to the other input terminal of the comparator 2; 7 is an A-D converting the output of the second switching circuit 6 into a digital signal;
The converter 8 is a central controller such as a microcomputer that checks the hold signal based on the output of the A-D converter 7 and also controls the first and second switching circuits 3 and 6, the A-D converter 7, etc. This is a control circuit consisting of a processing device.

Next, the operation will be explained.

At the time of sampling, the first and second switching circuits 3 and 6 close the same channel like the first switches 31 and 61 in response to each time-series analog input signal, and the input terminal 1 and the comparator 2 , first switching circuit 3,
A closed loop due to feedback is formed by the hold circuit 41 and the second switching circuit 6.
The comparator 2 works so that the input signal of the input terminal 1 and the output of the hold circuit 41 match, and the output of the hold circuit 41 rapidly tracks the input signal and matches the input signal, and outputs the output from the output terminal 51. It can be taken out.

After tracking is completed, the output of the second switching circuit 6 is converted into a digital signal by an A-D converter 7, and a check control circuit 8 checks the output value at the time of sampling.

Next, at the time of holding, all the switches of the first and second switching circuits 3 and 6 are opened, and holding is performed. After holding, the switch 61 of the second switching circuit 6 at this location is closed at predetermined intervals, and the A-D converter 7 converts the signal into a digital signal, which is then checked by the control circuit 8 during the hold.

In exactly the same way, for all channels, the first,
The second switching circuits 3 and 6 are operated to sample and hold the signals in the hold circuits 41, . . . , 4n, and the sampled signals are checked each time.

After the series ends, the second switching circuit 6 is operated at predetermined intervals until the next plurality of analog signal data arrive at the input terminal 1, and the A-D
Based on the output of the converter 7, the control circuit 8 checks the output signals of the hold circuits 41, . . . , 4n during hold. Note that a check circuit may be provided in place of the A-D converter 7 for checking. Also, each switch 31,..., 3n of the first switching circuit 3 and the hold circuit 41,...
..., 4n may be considered to constitute a sample and hold circuit.

(5) Summary of the Invention As described above, the present invention outputs a plurality of time-series analog signals through a comparator, a first switching circuit, a second switching circuit, and a hold circuit.
This is an analog output device in which the output is checked by a check circuit such as a -D converter.

(6) Effects of the invention In addition to checking the suitability of data during sampling, the output status during hold can also be checked at all times, and the output status is constantly monitored, improving reliability.

When checking for hardware failures, it is sufficient to check whether the actual output has a large deviation from the predetermined output, so the resolution of the A-D converter used as a check circuit is 4 bits or 8 bits. A low A/D converter is sufficient, and the A/D converter can be made at a low price, resulting in excellent cost performance.

The closed loop including the comparator eliminates the need to consider the offset of the sample and hold circuit, resulting in an inexpensive circuit that is fast and highly reliable.

[Brief explanation of the drawing]

FIG. 1 is a configuration explanatory diagram showing an embodiment of the present invention. 2...Comparator, 3,6...Switching circuit, 41-4
n...Hold circuit, 7...A-D converter, 8...
...control circuit.

Claims (1)

[Claims] 1. A comparator to which a plurality of time-series analog input signals are supplied to one input terminal, a first switching circuit that switches and selects the output of this comparator, and this first switching circuit. The outputs of these hold circuits are switched and selected in synchronization with the first switching circuit, and are supplied to the other input terminal of the comparator, so that the outputs of the hold circuits are rapidly converted into input signals. a second switching circuit that forms a closed loop based on feedback for matching; a check circuit that checks the output of the second switching circuit; and a control circuit that controls opening and closing of each switch of the first and second switching circuits. An analog output device characterized by comprising: 2. The analog output device according to claim 1, wherein an A-D converter is used as the check circuit, and the check is performed by the control circuit.